@ASTexas 

1) Can I still use QBDT and can I go back to it and dump this QBO? Does the new QBDT include payroll?

You can still purchase QB Desktop 2024 Pro Plus/Premier Plus + QB Desktop Payroll.

How many employees do you need to manage their payroll? If you have reached a certain number of employees, you should consider using QB Desktop Enterprise Gold.

Next you just need to convert the data back from QBO from the date you first used it. You will access your old QB Desktop files as an archive.

2) Why is there is no direct import to TT from QBO? And when will it be available?

Maybe their engineers are still having difficulty developing a reliable exporter. Otherwise, they have discontinued QB Desktop completely.